Janes.com is reporting that the original UK intention was to clear four MBDA Advanced Short-Range Air-to-Air Missiles (ASRAAMs) for internal carriage but this has been revised where it will be two internal and two external weapons instead.

The external ASRAAM configuration will be common accross all F-35 variants. This may generate interest among other F-35 customers that were considering using the AIM-9X Sidewinder.

Included for the external configuration will be a low observable pylon to keep the radar signature of the aircraft to a minimum.

Quoting Janes: The new ASRAAM plan is a 'work swap' that does away with the requirement to clear the ASRAAM on the F-35's two internal air-to-ground weapon stations. The integration team now has the more straightforward task of providing underwing carriage on stations 1 and 11.

While this configuration change is being sold as some kind of advantage, one has to wonder if the goal is to save cost in weapons clearance efforts during the System Development and Demonstration (SDD) phase which finishes with the F-35 being in the Block III configuration, or if extra internal ASRAAMs were not workable because of engineering problems.

Changing the weapons configuration for the finished Block III F-35 has been done before when in 2006, funding was provided to remove the external fuel tank clearance from the SDD program and push the Small Diameter Bomb (SDB) weapons clearance into F-35 Block III from it's original position in the F-35 Block IV plan. This 2006 funding also pulled the Wind Corrected Munitions Dispenser (CBU-105) from the SDD weapons chart.

Affordability has always been the goal of the F-35 program and it is critical that the SDD phase happen with minimal problems or cost annoyance. It is certain that other weapons clearances will be awarded throughout the life of the program as customer requirements merit. Which means it is possible to see an increased number of internal ASRAAMs and the external fuel tanks appear at a later date.

While traditionally thought of as a within-visual-range (WVR) air-to-air missile, with the ability to be cued to the target via the helmet system and radar, the ASRAAM missile has some beyond-visual-range (BVR) qualities.